Active compounds contained in agrochemicals such as insecticides, acaricides, fungicides, or herbicides, or in agents for controlling wood-destroying organisms such as termites are required to appropriately control elution thereof in order to maintain effects thereof or to reduce phytotoxicity in plants or toxicity in humans and animals.
There have been attempts to formulate active compounds having low water solubility so as to increase elution thereof. In contrast, there have been attempts to formulate active compounds having high water solubility so as to reduce the elution rate thereof.
Neonicotinoid-based compounds belong to a compound group which exhibits an insecticidal effect as a nicotinic acetylcholine receptor agonist or antagonist. Many compounds included therein have high water solubility. Therefore, reducing the phytotoxicity caused by application at a high concentration and maintaining effects over a long period of time by reducing the elution rate or the hoarding amount have been considered. As a method for adjusting the elution rate, a compound in which the neonicotinoid-based compound is included in a multimolecular host compound has been proposed (Patent Document 2). In addition, there is a case in which a change in elution properties is caused by formation of a co-crystal. For example, Patent Document 1 discloses a co-crystal composed of imidacloprid, which is an insecticide, and oxalic acid.